Design and Fabrication of cm-scale Tesla Turbines

Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission. This dissertation discusses the design and scaling characteristics of Tesla – or so-called " friction " – turbines, and offers design solutions for achieving optimum performance given the input specifications. The research covers turbines ranging from sub-watt power scavenging designs to watt-range mobile applications to kilowatt-range renewable energy applications. The characteristics of the turbine are demonstrated using micro fabrication, theoretical analysis, and ANSYS, COMSOL, and MATLAB simulations. A MATLAB GUI is provided for generating design specifications and turbine performance sensitivity. In Tesla turbines, the fluid profile and the length of the fluid path inside the rotor control the pressure drop and momentum transfer. In this research, analyses of rotor performance for incompressible flow are developed for different fluid profiles and fluid-path lengths. First, frictional losses in the nozzle and at the rotor-turbine interface are investigated, along with other turbine losses. These losses are then classified and modeled in terms of their relationship to head loss and shaft power loss, and investigated using MATLAB and COMSOL. As the turbine scales down, this scaled performance is evaluated and a constraint list for turbine hardware and operating parameters is derived. These results are used to optimize performance for the full range of millimeter to meter sized turbines. Tesla turbines at the scales covered in this dissertation (mm – m) are relatively easy to manufacture. The experimental mini-turbines presented in this research have two primary components, fabricated using commercially available technologies: 1) four 1 cm-diameter rotors with variation in number of disks, interdisk spacing, and effective area, and 2) a turbine enclosure with eight nozzles of varying area, …